Gas mask



S. HERMANN May 26, 1942.

GAS MASK Fil ed Sept. 9, 1941 INVENTOR m m m m wnz M fin m ATTORNEYPatented May 26, 1942 UNITED STATES PATENT OFFICE GAS MASK SiegwartHermann, New York, N. Y. Application September 9, 1941, Serial No.410,131

1 Claim.

This is a continuation in part; of patent application, Ser. No. 394,835,filed May 23, 1941.

My invention relates to improvements in gas masks. The object of myinvention is to improve the effect of gas masks by increasing the filtercapacity of the device without increasing respira tory difiiculties, butdecreasing even the breathing resistance of gas masks.

This is to be performed, according to this invention, by forcingaccessory air into the gas mask through a respiratory system comprisinga series of filters namely a pre-cleamng filter and a main filter, bothof them containing substances e. g. activated charcoal; suitable for thefiltering of the air to be inhaled. The filters of the respiratorysystem are separated by a length of tubing. A bellows pump, to beoperated preferably by the wearer of the gas mask, is placed before thepre-cleaning filter for .forcing the air through the system.Supplementary means for giving access to air from without are providedin the connection with the main filter, said means being active even ifthe pumping of air through the system is stopped.

I am aware of the fact that it has been already suggested to provide gasmasks with devices designed to force the air into the masks in order toovercome breathing difficulties due to the resistance of accumulatedfiltering material. However, in the known devices of this kind, thepumping can never be stopped because there are no other possibilitiesfor the air from without to pass through the respiratory system in themask. Therefore, the person using the mask will suffocate when thepumping in of air cannot be maintained.

Now, according to this invention, not only the air to be forced into therespiratory system, but also supplementary air, flows through the gasmask, the latter even when the device forcing the air in does not work.

In the annexed drawing several forms of the invention are showndiagrammatically. Like numbers denote like parts.

Fig, 1 is a View of a gas mask provided with a respiratory systemaccording to this invention.

Fig. 2 is a partially sectional View of the filtering part and a part ofthe hose of the device according to Fig. 1 showing the supplementary airsupply.

Fig. 3 shows a modification of the device according to Fig. 2.

Fig. 4 shows a modification of a part of Figs. 2 and 3, when valves areused.

Fig. 5 is an enlarged section through Fig. 4 on the line 55.

The gas mask l is provided with a regular main filter 2 and a length ofhose 3 connecting filter 2 with an additional pre-cleaning filter 4. Thebellows 5 are designed to supply air to the respiratory systemcomprising said main filter 2, hose 3 and pre-cleaning filter 4.

Means for supplying additional air from without to the main filter ofthe respiratory system are shown in Figs. 1, 2 and 3, respectively.

According to the performance of this invention, as shown in Figs. 1 and2, a rubber hose 3 is connected with the main filter 2 by means of an,extension 2 of the filter 2 over which hose 3 is drawn. A funnel or cone6 inserted in the upper part of hose 3 extends into filter 2 permittingthe air pressed through the system to enter this part of the gas mask.Corresponding holes 8 in the extension 2 and holes 9 in the rubber hose3 form a supplementary connection between the main filter and the airfrom without.

In the device as shown in Fig. 3 a relatively thin hose l3 connects thefilters 4 and 2. This hose is attached by means of a connection l2 to arigid tube ll extending into the main fi1ter'2. A jacket l0 connectedwith extension 2' surrounds tube ll. Corresponding holes H1 in thejacket l0, and 8 in the extension 2 are giving access to the air fromwithout to this modification of the respiratory system. I

I have found that by forcing air through a respiratory system asdescribed, air filtered in the pre-cleaningfilter as Well as in the mainfilter will flow through the system. If the user of the gas mask isforced to stop the pumping, sufiicient air can still be sucked throughthe breathing holes forming the supplementary air supply,

Figs. 4' and 5 show a modification of the device, according to thisinvention, comprising valves closing the breathing holes while an isforced through the respiratory system by the bellows and opening themwhen the pressure stops. The valves consist of aring I d inserted inextension 2'. To the ring I4 are attached small thin blades, e. g. ofrubber, for the purpose of closing the holes 8 of the extension. Whenthe air forced through the device meets the blades l5, they are pressedagainst the holes 8-, thus closing them. When the pressure stops by thesuction of breathing, a vacuum is created 'sufiicient to open the valvesand to give access to the air from without.

I have described preferred embodiments of my invention but it isunderstood that changes and omissions may be made without departing fromthe spirit of my invention.

What I claim is:

In a gas mask a respiratory system, comprisingv a main filter providedwith an extension, a rubber hose drawn over said in the upper part ofsaid rubber hose extending in the main filter, said extension and rubberhose being provided with holes forming a connection between the mainfilter and the air from without, a supplementary filterbeing connectedwith the main filter by said rubber hose and a pump for pressing airthrough the system placed before said supplementary filter.

SIEGWART HERMANN.

extension. a funnel inserted

